FOR American space science planners, Voyager 2's successful Neptune survey is a symbol of a more hopeful future. After a decade of delays and budget curtailments of long-planned programs, ``we are back in a period of time when the space science activities are active,'' says Lew Allen, director of the California Institute of Technology's Jet Propulsion Laboratory. JPL manages many planetary projects for the National Aeronautics and Space Administration (NASA).
Dr. Allen was referring partly to projects already under way. The Magellan Venus radar mapper is now on its way to that planet. It is working well and should arrive in a little less than a year. The Galileo Jupiter probe is ready for launch in October. Next March the Hubble space telescope should go into orbit. The joint United States/European sun-surveying Ulysses probe should depart Earth a little later. In 1992, the Mars Observer craft should head for the red planet.
But Allen was also referring to what he perceives as a more hospitable political climate for planning new space science ventures. It's a theme a number of space officials - including Vice President Dan Quayle - have emphasized while visiting JPL to view the Neptune encounter.
Geoffrey Briggs, director of NASA's Solar System exploration division, explained during a Planetary Society panel discussion that NASA's decision to use unmanned rockets and not rely exclusively on the shuttle for launches, plus the Bush administration's strong encouragement of the space program, have opened a new horizon for space science. It was ``obviously necessary for us to go back and take a look at what to do,'' Dr. Briggs said. Thus, he added, vigorous long-range planning has been going on for the past six to eight months.
As examples of what the planners are considering for missions in the latter half of the 1990s and beyond, Briggs cited the following:
A lunar orbiter to assay the moon's surface.
Perhaps other unmanned lunar missions in cooperation with the Soviet Union and with Japan, which is studying a mission to send a penetrating probe into the lunar surface.
Advanced Mars missions beyond Mars Observer. These might include hard-landing probes.
A Mars mission to land roving vehicles and return soil samples around 2001. This could be a collaborative project with the USSR.
Another outer planet mission to Uranus or Neptune with, perhaps, an atmospheric probe.
NASA planners have been studying such projects for many years. So far, little has come of this effort except more studies. But now, Briggs said he thinks there is an opportunity to bring some of this planning to fruition. The prospect for increased international participation is also encouraging, he added.
However, skeptics are watching congressional action on the administration's 1990 budget as an acid test of such optimism. The budget request includes funding to start two long-desired space science projects - the Comet Rendezvous Asteroid Flyby (CRAF) mission and the Cassini probe of the Saturn planetary system.
After being left on the budget-cutting table for several years, both projects have been approved by the administration and the House of Representatives. But Senate approval is not yet assured. If these projects make it through the budget process this year, even skeptics will see a brighter future for space science.
Mr. Quayle picked up this point during his JPL visit last Friday. He reiterated the administration's commitment to a strong space program, including space science. Asked if there would be money to back up this commitment, he said the administration thinks it has enough congressional support, even in the Senate, to sustain a strong space effort.
The most controversial part of the space budget is funding for manned flight, especially for continued development of the space station. If that requested funding is cut, space science might also suffer. Until NASA's 1990 budget finally is set, Allen, Briggs, and other planners who see new hope for space science won't know whether or not they are indulging wishful thinking.